(1) Arid and semiarid area means, in the context of alluvial valley floors, an area of the interior western United States, west of the 100th meridian west longitude, experiencing water deficits, where water use by native vegetation equals or exceeds that supplied by precipitation. All coalfields located in North Dakota west of the 100th meridian west longitude, all coalfields in Montana, Wyoming, Utah, Colorado, New Mexico, Idaho, Nevada, and Arizona, the Eagle Pass field in Texas, and the Stone Canyon and the Ione fields in California are in arid and semiarid areas, except that all coalfields located in the State of Washington west of the crest of the Cascade Mountain Range are not in arid or semiarid areas.

(2) Forestry (Forest Land). Includes land used or managed for the long-term production of wood, wood fiber, or wood derived products. All land which is capable of supporting a merchantable stand of timber and is not being actively used in a manner or for a use which is incompatible with timber growing is also included. Land used for facilities in support of forest harvest and management operations which is adjacent to or an integral part of these operations is also included.